Gun having sliding and interchangeable barrel



K. KEHNE GUNS HAVING SLIDING AND INTERCHANGEABLE BARRELS I March 28, 1944.

Filed Feb. 20, 1939 Patented Mar. 28, 1944 GUN HAVING SLIDING AND INTER- CHANGEABLE BARREL Karl Kehne, Berlin-Hegel, Germany; vested in the Alien Property Custodian Application February 20, 1939, Serial No. 257,508 In Germany October 7, 1935 2 Claims.

In guns having exchangeable barrels, barrelsecuring devices are known which automatically prevent a shot being fired when the barrel is not properly positioned in the gun or when the barrel is not properly locked. In the known arrangements a safety member, influenced by the coupling of the breech casing to the barrel, immediately locks the breech mechanism when the barrel is imperfectly coupled with the gun, so that it is impossible for the gun to be loaded unless the barrel has been coupled satisfactorily.

Furthermore, it is known in connection with guns having a reciprocating and exchangeable barrel to couple the barrel and a locking sleeve in such a manner that a guide member mounted in the gun casing engages, in the coupling position, in longitudinal grooves in the barrel and thus axially locates the barrel.

The invention is concerned with the problem of providing an improved safety-device of the last named type in such a manner that the manipulation of the safety-device itself and also of the barrel is simplified by means which control the assembling and dismounting movement. According to the invention, with this object in View at the rear end of the known longitudinal groove there is connected a guide groove which afiords positive guidance to the barrel over the entire course of its assembling and dismounting movement, and in which the guide member can enter after having been removed from the longitudinal groove. By giving the guide groove a suitable shape, according to the present invention an improvement in such barrel safety-devices is obtioned, whereby the gun is prevented from being cocked if the barrel has not been completely coupled, and the barrel is prevented from being clamped while it is imperfectly coupled, as is possible with the known safety devices. This result is obtained by the guide groove firstrunning transversely to the longitudinal groove on the barrel for a distance depending on the length of the barrel locking teeth, and then parallel to the said longitudinal groove as far as the rear end of the barrel.

The adjustment of the guide for the barrel to its normal position at the conclusion of the mounting of the barrel, calls attention from the outset to the proper or improper performance of the locking of the barrel. If the guide for the barrel does not engage in its normal or looking positionowing to a faulty barrel coupling or accidental omission owing to lack of attention, the guide will then coact with the transverse groove of the barrel to prevent the barrel from bein moved back to load the gun, which thus compels the gunner to bring the barrel fixing into a satisfactory coupled state before the gun can be fired.

The drawing illustrates a typical embodiment of the invention, namely as applied to a largecalibre machine gun having a reciprocating barre], a locked breech, and a barrel ifixingiof the bayonet catch type.

Fig. 1 is a longitudinal section through the middle part of the gun.

Fig. 2 is a cross section through the barrel at II-II, Fig. l but with the barrel guide shoe turned into alignment with the transverse groove.

Fig. 2a is a side view of a detail view of the guide.

Fig. 3 is a view, partly in section, of the breech end of the barrel.

The barrel a of the gun is adapted to be removed from the breech casing b, in theexample illustrated, from the front in known manner, but the invention is applicable to other removable barrel constructions. Patent No. 2,01%,184, issued September 10, 1935, shows one form of removable barrel and Patent No. 1,994,489. issued March 19, 1935, shows another structure.

The breech block is locked to the breech casing in in a manner which is usual in guns of the kind in which the breech block d does not open in order to eject a fired cartridge or for loading, and also just after a change of barrel has been'rnade, until it has covered a certain distance in the backward direction, in the condition in whichit is'closed and locked with the breech casing .21 and the barrel a.

In order that it may be fixed in positionthe barrel a has, at its rear end, two uniform rows of bayonet catches or teeth a1 distributed over its periphery, which locking teeth a; when thebarrel a has been inserted in the proper manner, engage over their entire width withcounterteeth hi on the breech casing b, this casing being so arranged as closely to embrace the barrel at its ;front portion over a considerable length.

In the coupled position shown in Fig, '1 the in the example shown, by flattening two sides of a cylindrical head.

On the knob f of the pin e which projects from the gun casing 0, there are provided projections f1 which engage in corresponding notches in the gun casing c and thus secure the shoe (:2 in the position necessary to enable it axially to guide the barrel. By raising the pin e against the pressure of the spring 61 until the projections f1, disengage from the notches in the casing, the knob f with the pin a can be turned, and after turning through 90 the pin e is held in a raised position which brings the foot of the shoe ea in alignment with a transverse groove g in the barrel casing serving to mount and dismount the barrel.

For this purpose, as may be seen from Figs. 2 and 3, there is provided at the junction of the longitudinal groove a2 and the peripheral or transverse groove 9 a cylindrical recess as the diameter of which corresponds to the maximum dimension of the shoe c2, and the depth of which is such that the walls of the recess extend to the base of the groove cm which runs longitudinally on the barrel casing. The arrangement of the recess as and the projections f1 necessitates the raising and the turning of the shoe 62 into the position necessary to enable the barrel to be changed and in this position the base of the shoe a2 is held level withthe bottom of the transverse groove 9, but is not high enough to be flush with the peripheral surface of the barrel. The sliding shoe ez, when in the raised and turned position, thereby forms, in the assembly and dismounting of the barrel, an abutment that prevents the barrel from being drawn back when the coupling of the barrel has not been properly carried out and secured and thus precludes the possibility of the gun being loaded in such case.

Into the transverse groove g, there opens another longitudinal groove 91 which extends to the rear end of the barrel. The length of the transverse groove g depends on the peripheral length of the locking teeth on on the barrel, while the width of the groove g1 corresponds to the greater dimension of the slide shoe e2.

After the pin e has been raised and turned through 90, the slide shoe stands in the position shown in Figs. 2 and 3, i. e. with its narrow side disposed to the groove 9 so that an unbolting, pivotal movement of the barrel a can take place. The disengagement of the barrel teeth (11 from the 'counterteeth D1 in the breech casing is completed as soon as the longitudinal groove 91 of the barrel, which extends rearwards at right angles to the groove 9, comes opposite the shoe 62. Any further pivotal movement of the barrel in the unlocking direction is thus prevented. Now, the barrel can be drawn forward axially and withdrawn from the breech casing b and, therefore, from the gun.

A new barrel can be inserted only when it occupies an angular position which is determined by the guiding of the slide shoe e2 in the longitudinal groove 91, when, the breech casing I) being in its forward end position in the gun, the insertion of the barrel automatically brings the teeth a1 opposite the gaps of the locking teeth In of the breech casing 17. The limitation of the inward movement of the barrel, to the position in which the teeth of the barrel a and of the breech casing b are correctly relatively disposed to enable the barrel and breech casing to be locked together, which is effected by the striking of the shoe e2 against the front wall of the transverse groove y, and its accurate centering in the junction of the grooves g and a2, permitting turning movement as necessary for the locking operation. When the barrel attains the completely coupled position, this position is indicated by the abutment of the shoe 62 against the walls of the circular recess as. If now the shoe e2 is turned back through until the projections f1 engage in the grooves in the casing, the barrel a is fully secured and the gun is again ready for loading.

In the present case the locking teeth on the barrel a and the breech casing 27 have no screw pitch, so that when the barrel is inserted its linear inward movement is limited by the rear end of the barrel striking against the shoulder in of the breech casing b.

If the locking teeth of the barrel 0. and the breech casing b have a coarse screw pitch, for instance in order to loosen the cartridge case during the unbolting operation, then, naturally, the transverse groove 9 must also be given a corresponding inclination. In this case the barrel would be prevented from being inserted further than the proper locking position merely by the co-action of the shoe c2 and the groove g.

I claim:

1. An automatic firearm of the reciprocating exchangeable barrel type comprising a firearm casing, a breech casing slirlable therein, a removable barrel, bayonet joint coupling means on said barrel and breech casing whereby said barrel is removably mounted, and a guide member in said firearm casing settable into normal and unlocking positions projecting different amounts from said casing, said guide member having a cylindrical guide shoe with opposed parallel flats, and said barrel having therein a guide groove of a width corresponding to the flattened portion of the guide shoe, said groove extending longitudinally forwardly of the barrel from near its rear end for a length corresponding to the travel of the barrel in firing and being engaged by said guide shoe only when the guide member is set in normal position, 'a transverse groove joined at one end to said longitudinal guide groove, said transverse groove being of length corresponding to the turning movement to operate the bayonet joint,'and an additional longitudmal groove joined to the other end of said transversegroove and extending through to the rear end of said barrel, said transverse and additional longitudinal grooves being of a depth corresponding to the projection of the guide shoe when set in unlocking position and of widths for cooperation with said guide shoe to guide the barrel in coupling and uncoupling said bayonet joint means.

2. A firearm according to claim 1, in which the longitudinal guide groove and the transverse groove are joined by a cylindrical recess of a diameter corresponding to the diameter of the cylindrical part of the guide shoe and having its walls extending to the bottom of the longitudinal groove.

KARL KEI-INE. 

